1. Technical Field
This disclosure relates generally to medical imaging.
2. Background of the Related Art
Medical imaging is the technique used to create images of the human body or parts thereof for clinical purposes (medical procedures that seek to reveal, to diagnose or to examine disease) or medical science (including the study of normal anatomy and physiology). Computer tomography (CT) and magnetic resonance imaging (MRI) are two of the most common approaches. These techniques generate a set of individual 2D images that can be displayed in a 3D visualization as a “volume dataset.” Typically, however, the extent of the 3D visualization is limited to “orbiting” and “zooming.” In an “orbit” mode, the view of the object being rendered is like an orbiting satellite in that the viewer can move around the object being viewed from any angle but cannot look “out” from a position within the object. A zoom operation provides the viewer with additional useful details about the object; however, zooming does not enable the viewer to move down to a surface or inside of a volume. Thus, the orbit and zoom approach has limited applicability for rendering and viewing a volume medical dataset.
Volume rendering is the process by which a series of images that are stacked upon one another to form a volume of data is eventually rendered to the screen to form an image that is able to be viewed by a person. There are numerous methods and strategies to accomplish the previously mentioned goal. Ray tracing is the process by which a virtual ray is fired into a scene or volume from a virtual camera's position and direction in order to calculate a color for one pixel in the rendered image. Necessarily, numerous rays are traced to form the final image. A ray is traced starting at the virtual camera position and is fired in the virtual camera direction plus an angle based on the pixel position in image space. The ray will eventually return a color, which represents the scene or volume as viewed from this pixel. This returned color is calculated from what is encountered in the volume by the fired ray.